Update license to MIT

[jwmbeenakker]

Proposed change

As discussed in #57, we want to change the license of ZOSPy to MIT, to better facilitate future (re-)use.

Type of change

Modified license to MIT

• Example (a notebook demonstrating how to use ZOSPy for a specific application)
• Bugfix (non-breaking change which fixes an issue)
• New analysis (a wrapper around an OpticStudio analysis)
• New feature (other than an analysis)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests
• Documentation (improvement of either the docstrings or the documentation website)

Additional information

not applicable

Related issues

closes #57

Checklist

• I have followed the contribution guidelines
• The code has been linted, formatted and tested locally using tox.
• Local tests pass. Please fix any problems before opening a PR. If this is not possible, specify what doesn't work and why you can't fix it.
• I added new tests for any features contributed, or updated existing tests.
• I updated CHANGELOG.md with my changes (except for refactorings and changes in the documentation).

If you contributed an analysis:

• I did not use AttrDicts for the analysis result data (please use dataclasses instead).

If you contributed an example:

• I contributed my example as a Jupyter notebook.

[crnh]

@jwmbeenakker this PR has successfully shown that autoclosing discussions from a PR is not a feature (autoclosing is only possible with issues), so #57 needs to be closed manually.